CN102170643B - A ZigBee channel dynamic selection method based on real-time availability - Google Patents

Abstract

The invention discloses a Zigbee information channel dynamic selection method based on real-time availability. In the invention, the concept of information channel availability is provided for the first time, the information channel availability is updated by the availability algorithm in real time, and information channels can be dynamically selected according to availability sequence in an information channel resource pool, which is marked by a broken line in the figure. Parameters for the information channel availability indicate the vacancy rate and communication quality of the information channel and show practical available conditions of the information channel. Therefore, the parameters for the information channel availability can be used for guiding selection of the information channel in practical data transmission, so as to provide a communication support, increase the data transmission success rate, and reduce the collision rate and retransmission rate to the largest extent. Based on the vacancy rate and quality of the information channel, data transmission results and other parameters, the invention provides the real-time availability algorithm. The real-time availability algorithm not only provides a high-quality vacant information channel with more selection chances, but also ensures the fairness of information channel selection to the largest extent and enables the information channel to be selected by relative fair chance, thereby improving the utilization rate of the information channel. In the invention, the strategy to build the information resource pool to manage information channel resources is provided; information channels are sequenced based on the parameters for the information channel availability; and the ZigBee information channel is selected according to the sequencing result, thereby realizing the Zigbee information channel dynamic selection method based on real-time availability.

Description

A ZigBee channel dynamic selection method based on real-time availability

technical field

This patent relates to a novel dynamic selection method of ZigBee channels based on real-time availability, which belongs to the field of dynamic utilization of channel spectrum resources.

Background technique

ZigBee technology is an emerging short-distance wireless communication technology. Its main application field is Low Rate Wireless Personal Area Network (LRWPAN, Low Rate Wireless Personal Area Network). Typical features are short-distance, low power consumption, low cost, and low transmission. rate. The ZigBee/IEEE 802.15.4 (hereinafter referred to as ZigBee) standard is established on the basis of the IEEE 802.15.4 standard. ZigBee equipment should include the MAC layer (media access control layer) and PHY layer (physical layer) of IEEE 802.15.4 ), and the ZigBee stack layer (network layer, application layer and security service provider layer). The IEEE 802.15.4 standard defines the MAC layer and the PHY layer of the OSI (Open System Interconnection) model for the ZigBee standard. The PHY layer defines the characteristics that the wireless radio frequency should have. It supports two different radio frequency signals, located in the 2450MHz band and the 868/915MHz band respectively. The 2450MHz band radio frequency supports 16 channels with a data rate of 250kbps. In the 868/915MHz band, 868MHz supports 1 channel with a data rate of 20kbps, and 915MHz supports 10 channels with a data rate of 40kbps.

At present, in order to realize applications such as the Internet of Things, sensor networks, intelligent wireless control, and intelligent buildings, short-range wireless communication technology standards for wireless area networks (WAN, Wireless Area Network) have been developed rapidly. Like the ZigBee protocol, typical wireless LAN technology standards such as Bluetooth (Bluetooth), Wireless USB (WirelessUSB), wireless LAN Wi-Fi (IEEE 802.11b/g), etc., all choose 2.4GHz (2.4～2.483GHz) ISM ( Industrial, scientific, medical) frequency bands make the ISM frequency band increasingly crowded. With the large-scale application of the Internet of Things and sensor networks, the demand for the number of channels in a local area will increase sharply, and the overlapping coverage of the spectrum will lead to an increase in mutual interference between communication systems, coupled with the existence of interference sources such as cordless phones and microwave ovens , the collision rate and retransmission rate also increase sharply, seriously affecting the utilization rate of the channel and the success rate of data transmission.

To sum up, spectrum resources and channel resources will become more and more precious. Although the ZigBee protocol stipulates 27 available channels in different frequency bands, the current channel selection of ZigBee only considers simple channel evaluation parameters, and its channel selection is based on a preset fixed mode. A large number of measurements and investigations on the actual utilization rate of spectrum resources and channels show that in the fixed channel mode, channels are not occupied most of the time, and some are only occupied for part of the time. In some environments where electromagnetic mutual interference is serious, some channels are not suitable as communication channels. Therefore, in the ZigBee protocol, if parameters such as channel idle rate and channel quality can be comprehensively inspected in real time to realize dynamic channel utilization, it can not only alleviate the congestion of public frequency bands, but also improve channel utilization and data transmission success rate, reduce Channel interference in turn reduces the collision rate and retransmission rate.

Contents of the invention

The purpose of the present invention is to provide a method for dynamically selecting ZigBee channels based on real-time availability. This channel selection method based on availability can improve the transmission success rate, reduce the collision rate and retransmission rate; at the same time, the real-time calculation and update algorithm of availability can maximize channel selection on the basis of selecting the maximum availability fairness and improve channel utilization.

To achieve the above-mentioned purpose, the present invention adopts following technical scheme:

A ZigBee channel selection method based on real-time availability, is characterized in that comprising the following steps:

Step 1, create a channel resource library;

Step 2, number all channels in the channel resource library, and set parameters such as channel idle rate, channel quality and channel availability for all numbered channels;

Step 3, traverse and detect the idle conditions and channel quality parameters of all channels, and calculate the statistical idle probability of the channel;

Step 4, according to step 3, calculate and update the channel availability of all numbers;

Step 5, sort all the channels in the channel resource library according to the availability of each channel from large to small;

Step 6, waiting state, if there is data transmission, go to step 7, otherwise continue waiting state;

Step 7. Monitor the channel with the maximum availability in the channel resource bank. If it is idle, occupy this channel for data transmission. If the channel is not idle at this time, monitor the next channel in the sorted channel resource bank. By analogy, until an idle channel is detected and data transmission is performed, otherwise the algorithm ends or the algorithm is re-run;

Step 8, detecting the data transmission result in step 7, and using the real-time availability algorithm to estimate the idle rate and channel quality of each channel at the next moment according to the detected channel idle status and channel statistical idle probability and other parameters in step 7;

Step 9, according to step 8, calculate the channel availability of each channel at the next moment, then jump to step 5, and repeatedly execute steps 5 to 8.

in,

In the step 1, the channel resource library is a collection of parameters of all channels available in the ZigBee protocol. As shown in FIG. 1 , each channel parameter in the channel resource library includes channel number, channel idle rate, channel quality, channel availability and so on.

In the step 2, assuming that the number of all available channels of ZigBee in the channel resource library is n [n is a non-zero natural number], all available channels are numbered sequentially from 1 to n by the parameter i. Set λ _i (t)[i=1, 2...n] to represent the channel idle probability of channel number i at time t, and set β _i (t)[i=1, 2...n] to represent the channel number as The channel quality of the channel i. The definition η _i (t)=λ _i (t)×β _i (t) [i=1, 2...n] represents the channel availability of the channel number i at time t. Set a to represent the statistical idle probability of the channel, set w to represent a constant less than 0.5 (the reasonable value of w should be determined according to the specific application scenario), and set s to represent the data transmission result (if the data transmission is correct, s=1, otherwise the data Transmission failed s=0). This operation is performed after the channel resource library is created in step 1.

In the step 3, all channels in the channel resource library are traversed to detect their idle conditions and channel quality parameters, if the channel i is idle, then λ _i (t)=1, otherwise λ _i (t)=0, and record the corresponding channel quality Parameter β _i (t), statistical idle channels, ie the number of channels where λ _i (t) = 1 is m, calculate channel statistical idle probability a = m/n, so far the algorithm initialization is completed.

In said step 4, according to step 3, use η _i (t)=λ _i (t)×β _i (t)[i=1, 2...n] to calculate the channel availability of channel i, and update all The channel availability of the channel. The channel availability parameter integrates the channel idle rate and channel quality parameters, and it can objectively reflect the actual available state of the channel.

In the step 5, sort all numbered channels in descending order according to the availability η _i (t) of all channels in the channel resource library, so far the channel resource library based on channel availability is established.

In the step 6, in this step, if there is no demand for data transmission, it will be in a waiting state until there is data transmission, then go to step 7.

In said step 7, select the channel with the maximum availability in the channel resource bank to monitor, if it is in an idle state, then occupy this channel for data transmission, and mark this channel λ _i (t)=1, otherwise the channel is not idle at this time , mark λ _i (t) = 0, monitor the next channel in the channel resource bank, if it is idle, occupy this channel for data transmission, and mark the relevant parameters, otherwise continue to monitor the next channel in the channel resource bank Monitor, and so on, until an idle channel is detected for data transmission. If no idle channel is detected after traversing the entire channel resource bank, choose to end or rerun the algorithm.

In said step 8, the data transmission result s is detected, and according to parameters such as the idle state λ _i (t) of the detected channel and the statistical idle probability a of the channel in step 7, the real-time availability algorithm is used to estimate the channel i [i=1, 2 ...n] The idle rate λ _i (t+1) and channel quality β _i (t+1) at time t+1, the real-time availability algorithm is specifically expressed as follows:

Case 1: If the idle state of channel i is detected at time t, if λ _i (t)=1 (idle), and s=1, then at time t+1, the estimated probability of idle state of channel i is λ _i (t +1)=1, and set the channel quality β _i (t+1)=β _i (t);

Case 2: If the idle state of channel i is detected at time t, if λ _i (t)=1 (idle), but s=0, then at time t+1, the estimated probability of channel i being idle is λ _i (t+ 1)=wa, and re-detect the channel quality β _i (t+1);

Case 3: If the idle state of the channel is detected at time t, if λ _i (t)=0 (non-idle), then at time t+1, the estimated probability of channel i being idle is λ _i (t+1)=0, And set channel quality β _i (t+1)=β _i (t);

Situation 4 If the idle state of channel i is not detected at time t, if λ _i (t)≥a, then at time t+1, the estimated probability of channel i being idle is λ _i (t+1)=λ _i (t) , and set channel quality β _i (t+1)=β _i (t); if λ _i (t)<a, then at time t+1, the estimated idle probability of channel i is λ _i (t+1) =λ _i (t)+wa, and set its channel quality β _i (t+1)=β _i (t), where the stepwise growth of idle estimation probability guarantees the chance of non-idle channels being selected. At the same time, the blind increase of idle estimation probability is prevented by limiting the maximum value of idle estimation probability, thereby ensuring the fairness of channel selection.

In said step 9, according to the idle rate λ _i (t+1) and the channel quality β _i (t+1) of each channel t+1 moment in step 8, use η _i (t+1)=λ _i (t +1)×β _i (t+1)[i=1, 2...n] calculates the channel availability of all channels in the channel resource library at time t+1, and uses η _i (t+1) to update all channels in the channel resource library channel availability η _i (t), and then jump to step 5.

The ZigBee channel allocation method based on real-time availability provided by the present invention provides a solution for dynamic utilization of channels. On the one hand, a channel resource library is set up, and channel availability parameters are set for all channel resources. Because the channel availability takes the channel idle probability and channel quality into consideration, the channel is selected according to the principle of maximum availability, which can provide reliable communication with the greatest probability, improve the success rate of data transmission, and reduce the transmission failure rate and retransmission rate; on the other hand, The present invention proposes a new real-time availability algorithm to update the channel availability parameters in the channel resource library, under the premise of fully considering channel idleness and channel quality, it not only ensures the fairness of channel selection, but also realizes the reuse of channel resources , thereby improving channel utilization.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Figure 1 is a ZigBee channel resource library diagram based on channel availability.

Fig. 2 is a schematic diagram of a ZigBee channel selection method based on real-time availability.

Fig. 3 is a flow chart of the ZigBee channel selection method based on real-time availability.

Detailed ways

As shown in Figure 1, assume that the total number of ZigBee channels is n, and all channels are numbered sequentially from 1 to n, and the channel idle rate λ _i (t) and channel quality defined as channel number i[i=1, 2...n] are β _i (t), the channel availability of channel i is defined as η _i (t) = λ _i (t) × β _i (t), and the channel availability parameter comprehensively reflects the idle rate and channel quality of the channel.

Fig. 2 is a schematic diagram of the ZigBee channel selection method based on real-time availability, and the content of the dotted frame in the figure embodies the innovation core of the present invention, that is, dynamically selects channels according to the availability sorting in the channel resource library, and utilizes real-time available The degree algorithm dynamically updates the channel availability. Its detailed process is shown in Figure 3, and the process of a ZigBee device dynamically selecting a suitable channel as a data transmission channel in a complex radio environment is taken as an example below to further demonstrate the present invention. Its specific implementation is as follows:

1) The present invention is an algorithm for dynamically selecting channels based on real-time availability, and a channel resource library is required to represent and store the channel parameters used. Therefore, the first step of the algorithm is to "create a channel resource library";

2) After the channel resource bank is determined, the algorithm needs to be initialized, which mainly includes the setting of parameters necessary for the algorithm to run, such as channel idle rate and channel quality. Steps 2 to 3 in the ZigBee channel dynamic selection method based on real-time availability (step 2: number the channel and set related parameters; step 3: obtain the channel idle state and channel quality parameters, and calculate the statistical idle probability of the channel.) It is completed in the algorithm initialization phase, so far the algorithm initialization is completed;

3) The ZigBee device calculates and updates the channel availability of all channels in the channel resource library, and sorts all channels in descending order according to the channel availability, and completes the sorted channel resource library based on the current channel availability. Enter the waiting state (step 4: update the channel availability; step 5: sort the availability; step 6, enter the waiting state);

4) If the ZigBee device has data to transmit, select the first channel from the sorted channel resource library to monitor, if it is idle, occupy this channel and transmit data, and go to the next step; otherwise, continue to monitor A channel, until there is an idle channel, then occupy this channel and carry out data transmission; if no idle channel is detected after traversing all the channel resource banks, then end the algorithm or restart the algorithm (as described in step 7);

5) After the ZigBee device completes the data transmission, immediately detect the result of the data transmission, and utilize the real-time availability algorithm to calculate the channel idle rate and channel quality (as described in step 8) of all channels in the channel resource bank at the next moment;

6) Calculating and updating the availability parameters in the channel resource library (as described in step 4).

The availability-based ZigBee channel selection method of the present invention has been described in detail above, but the specific implementation form of the present invention is not limited thereto. For those skilled in the art, various obvious changes made to the method of the present invention without departing from the spirit of the method and the scope of the claims are within the protection scope of the present invention.

Claims (2)

1. A ZigBee channel dynamic selection method based on real-time availability is characterized in that a method for selecting a transmission channel according to the channel availability is characterized in that the method comprises the following implementation steps:

1) creating a channel resource library, namely creating channel resource library management channel resources through channel idle probability, channel quality and channel availability; setting the number of all available channels of ZigBee in channel resource library as n [ n is non-zero natural number]A plurality of; the parameter i represents the number of the channel; parameter lambda_i(t)[i＝1，2...n]The channel idle probability of the channel with the number i at the time t is represented; parameter(s)β_i(t)[i＝1，2...n]Indicating the channel quality of the channel with time t number i; parameter eta_i(t)[i＝1，2...n]Indicating the channel availability of the channel with the time t number i; the parameter a represents the channel statistical idle probability; the parameter w represents a constant less than 0.5; the parameter s represents a data transmission result (if the data transmission is correct, s is equal to 1, otherwise, s is equal to 0);

2) ergodically detecting the idle condition of all channels (if channel i is idle, lambda is_i(t) 1, otherwise λ_i(t) ═ 0) and channel quality (β)_i(t)), according to η_i(t)＝λ_i(t)×β_i(t) calculating channel availability; statistics of free channels, i.e. lambda_iThe number of the channels with (t) ═ 1 is m, and the statistical idle probability a of the channels is calculated to be m/n, so that the algorithm initialization is completed;

3) sorting the channels in the channel resource library from large to small according to the channel availability parameters of each channel;

4) monitoring the channel with the maximum availability in the channel resource library, if the channel is in an idle state, occupying the channel for data transmission, if the channel is not idle, monitoring the next channel in the sequenced channel resource library, and so on until the idle channel is detected, and performing data transmission, otherwise, ending the algorithm or re-operating the algorithm;

5) and counting parameters such as channel idle probability and the like based on the channel monitoring idle condition, and updating the idle probability and the channel quality of each channel through a real-time availability algorithm.

2. In a method for dynamically selecting a ZigBee channel based on real-time availability as claimed in claim 1, the channel idle probability, the channel quality and the channel availability at the time t +1 are updated by a real-time availability algorithm, which is characterized by the following four situations:

case 1: if the idle state of channel i is detected at time t, if λ_i(t) 1 (idle) and s 1, then at time t +1 the probability of idle state for channel i is λ_i(t +1) ═ 1, and channel quality β is set_i(t+1)＝β_i(t)；

Case 2: if the idle state of channel i is detected at time t, if λ_iIf (t) is 1 (idle), but s is 0, then at time t +1, the probability of channel i being idle is λ_i(t +1) ═ wa, and the channel quality β is redetected_i(t+1)；

Case 3: if the idle state of the channel is detected at time t, if λ_i(t) ═ 0 (non-idle), then at time t +1, the probability of idleness of channel i is λ_i(t +1) ═ 0, and channel quality β is set_i(t+1)＝β_i(t)；

Case 4: if the idle state of channel i is not detected at time t, if λ_i(t) ≧ a, then at time t +1, the channel i has an idle probability of λ_i(t+1)＝λ_i(t) and setting a channel quality β_i(t+1)＝β_i(t); if λ_i(t) < a, then at time t +1, the channel i has an idle probability of λ_i(t+1)＝λ_i(t) + wa, and setting its channel quality β_i(t+1)＝β_i(t)。